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So, Wednesday marked seven years to the day that I took delivery of my '95 Cutlass Supreme convertible, which also means the registration is due for renewal. When I took it in for that today, I was informed that since the car is now 30 years old, the state of North Carolina considers it to be "vintage vehicle," and such it no longer requires an annual state safety inspection. Fine by me, that's a few dollars I didn't have to spend today. I also believe the Antique Automobile Club of America would consider it an antique.

Step #1: Buy a new Swap Harness (if available) or an 1998 L36 LTZ/Z34 harness and C100 plug and get wiring yourself.

A clicker-type torque wrench is going to be way better than a beam. I've had apart a couple high-mileage LQ1s and as Schurkey has said, you'll probably find the valves need work. I would also second replacing the oil pump drive gasket whether it needs it or not since it's only accessible with the head off. You mentioned you know it needs valve stem seals. I bet if you look closely at the heads when they're off, you will find some valve guides have sunk into the ports, particularly the exhaust ones, which get much hotter than the intake. It's a big problem on the LQ1. It gets diagnosed as bad valve stem seals, but in reality the problem is the seals are just riding up and down with the valve since they aren't affixed (or aren't affixed well) to the guide. Any sunken guides will need replaced. When apart, I have always put snap rings all my guides, whether they're new or reused ones, before assembling so that they will never sink down into the head. You'll need a special tool to cut the groove in the guides for the snap ring, but a cylinder head machine shop should be able to do that for you. The bottom end of an LQ1 is stout they they last a long time with maintenance. My DD 96 Z34 is up 230k and runs great.

You need the following parts from a 98-99 Monte Carlo z34/ lumina ltz wiring harnesses power steering lines exhaust downpipe (or have one made) heater core hoses if possible the alternator bracket/tensioner for the right angle heater hose connectors under alternator not 100% needed but nice to have. Other items Need to use the inner axle cups from the donor car and the outer shafts of the original cutlass Motor mounts bolt in no issues Donor car rad and hoses work Donor car auto trans cooler lines work Need a pcm tune to disable VATS. Once you have the parts, pcm and the wiring harness figured out it’s drop in You need to use the original subframe The best advice I can give you for the wiring, and OBD2, is to get a factory service manual from the 98/98 monte carlo/Lumina and for your year of Cutlass. You'll need to spend time ensuring each wire at the C100 connector matches from the monte carlo harness to the dash harness of the cutlass. I would say 75% of the wires will be the same, and you'll need to move or add 25% of the wires. You will also need to run 2 wires inside the cab for the OBD port, and I ran one into the cab for the tach as well. Not sure if that is 100% needed, but it works for me! There used to be plenty of information out there on this swap. I'm not sure if the old forums or posts have disappeared but this should get you going in the right direction. Once you get working, I'm sure you'll come across specific issues, post them here and I'll do my best to help as I can. Also check out this guys thread, for some troubles with this swap and how to overcome them (not my thread, but it'll help you see what you're in for).

Is your Trans in good shape? I swapped Series III using my 3:43 FDR Trans from LQ1. Used 1997 GP PCM with 96 harness, and had Milzy reprogram for 3:43. I have a post about differences

Yep, I've done much research on this. It's true, you do NOT want to get the L67 from anything other than a W-body unless you want to make more work for yourself (and nobody wants to do that). It can be done, but you'll be swapping a LOT of brackets and other misc pieces. The tach in the Cutlass Supreme with digital gauges cluster will NOT work after an L67 swap using the L67's PCM. This is probably the same with the 88-91 Regal digital gauges cluster since I believe it was also made by Nippon Denso. It WILL work fine if you have a 92+ with the analog dash and tach. Anyway, the Denso cluster gets its tach signal from the ALDL serial data line. The L67 PCM has this (they call it "UART serial data"). Problem is, the tach data is not present in the datastream. You COULD use a 3800 Series I SC PCM and it will probably have the tach signal... even that's not definite, but I think it does. However, you won't be able to use the 4T65-E tranny and the PCM's calibration isn't ideal for the engine, but it WILL work. You could also run the original ECM in parallel with the new PCM and just hook up enough wires to get a tach signal into the ECM, and the ECM will put the appropriate tach data onto the serial data line. Since the original poster wants to use a 5-speed, I think a 3800 Series I SC PCM would be the ideal way to go. Use the 3800 Series I SC PCM, wiring, etc. on the 3800 Series II SC engine. Make sure the PCM is a black sheetmetal formed box that looks like the old one. If it's a cast looking thing and much bigger than the old one, it's an OBD-II PCM which likely won't supply a tach signal on the serial data bus.